I welded an Elsie fore-end retainer spring that was broken in the middle(there was a inclusion in the metal at the break)) I used TIG with music wire as the filler. After grinding and polishing, I heat-treated as if it had been annealed. A few stress cycles in a vise proved the weld was sound so I reinstalled it. That was several years ago and as far as I know it is still in sevice.

OB